Electron Spin Relaxation Times in Sodium-Ammonia Solutions

Abstract

The transverse and longitudinal relaxation times (${T}_{2}$ and ${T}_{1}$) were measured at 17.4 Mc/sec (6.2 gauss) by rf pulse techniques. ${T}_{2}$ was obtained by measuring the decay time of the free-induction signal following a 90\ifmmode^\circ\else\textdegree\fi{} flip, and was found to vary from about 3.2 \ensuremath{\mu}sec to 0.7 \ensuremath{\mu}sec as the sample concentration varied from 1.1 to 25.9 mg Na/g N${\mathrm{H}}_{3}$. ${T}_{1}$ was measured by the 180\ifmmode^\circ\else\textdegree\fi{}-90\ifmmode^\circ\else\textdegree\fi{} method over a concentration range of 4.9 to 16.9 mg Na/g N${\mathrm{H}}_{3}$. It was found that ${T}_{1}$ equals ${T}_{2}$ in this range to within about \ifmmode\pm\else\textpm\fi{}10%, in accord with the theory of Bloembergen, Purcell, and Pound. Spin echoes from electrons were observed. Descriptions of the apparatus and the method of preparing the samples are included.